In general, an integrated gasification combined cycle (IGCC) power plant may efficiently generate cleaner energy from a hydrocarbon feedstock such as coal.
According to an IGCC technology, the hydrocarbon feedstock may react with oxygen in a gasifier to change into a gas mixture, that is, syngas.
The gasifier includes an external pressure vessel and an internal membrane wall having a cylinder shape and provided in the external pressure vessel to surround a gasification reaction area.
The membrane wall, which protects the external pressure vessel from a high reaction temperature, is produced using a series of tubes like a water-cooled wall of a boiler furnace.
Coals and oxygen are introduced into the gasification area of the gasifier to form the syngas including hydrogen and carbon monoxide.
A mineral material contained in coals forms liquid slag that flows down into a water receiving part provided on the bottom of the gasifier along a hot internal surface of a transfer duct.
The syngas cooled in the gasifier as described above is introduced into a syngas cooler and cooled to a low temperature to generate high pressure and middle pressure steams.
The syngas cooler may include a long external vessel to receive the syngas into the syngas cooler, and a cylindrical membrane wall may be employed in the external vessel to circulate, for example a coolant.
Meanwhile, a communication part may be interposed between the gasifier and the cooler so that the gasifier communicates with the cooler. The communication part may include a membrane wall (transfer duct) produced in the shape of a cylindrical duct formed by coupling a plurality of tubes having a coolant flowing therein to each other and provided at the intermediate portion thereof with a curved part, similarly to the membrane wall employed in the gasifier and the cooler.
Hereinafter, a procedure of producing the membrane wall having the shape of the cylindrical duct according to the related art will be described.
FIG. 1 is a view to explain the state that the cylindrical membrane wall according to the related art is produced.
Referring to FIG. 1, a plurality of unit sub-bundles 1 are produced by welding a plurality of tubes 1a to each other. In this case, three tubes 1a or less are employed in the unit sub-bundle 10 to have a curvature corresponding to that of the cylindrical membrane wall.
FIG. 2 is a view showing the state that a turn buckle is employed when producing the membrane wall according to the related art, and FIG. 3 is a view showing the state that a jig is employed when producing the membrane wall according to the related art.
Referring to FIGS. 2 and 3, a plurality of sub-bundles 1 produced by welding three tubes 1a to each other are fixed to a cylindrical jig 5 by a turn buckle 7.
Thereafter, a worker manually carries out a welding work to couple the unit sub-bundles 1 to each other. After the welding work has been finished, the worker removes the turn buckle 7 and the jig 5 to complete the cylindrical membrane wall.
As described above, according to the related art, after disposing the unit sub-bundles 1 in the cylindrical jig 5, the sub-bundles 1 are manually welded to each other so that the cylindrical membrane wall having a curved surface is produced.
Accordingly, there is a difficulty in producing the sub-bundle 1 by coupling at least three tubes 1a to each other in order to form a desirable curved surface. Therefore, the number of processes to produce the sub-bundles 1 may be increased, and the number of works to couple the sub-bundles 1 may be increased.
In addition, as each sub-bundle 1 is fixed to the cylindrical jig 5 by the turn buckle 5, the work to fix the turn buckle 5 is frequently performed, and the usage of the turn buckle 5 is increased.
In addition, as the sub-bundles are manually coupled to each other by the worker, the coupling errors may occur, and deformation and residual stress may occur in the welding work.
Meanwhile, the transfer duct interposed between the gasifier and the syngas cooler and manufactured in the shape of a cylinder having a curved part is manufactured through the following processes.
First, after primarily bending a unit pipe assembly, which is configured by coupling a pair of pipes to each other through a pin, with a predetermined curvature radius, the bent unit pipe assembly is secondarily tilted, so that a bending product tilted with the predetermined curvature radius may be formed.
Next, bent unit pipe assemblies are welded to each other in a longitudinal direction to manufacture the transfer duct in the shape of a cylinder having a curved part.
In order to form the transfer duct according to the related art, which is the bending product, as described above, after primarily bending the unit pipe assembly with a predetermined curvature radius, the unit pipe assembly, which is primarily bent, is secondarily pressed, so that the unit pipe assembly may be tilted.
That is to say, in the primary bending process, a pair of pipes constituting the unit pipe assembly are maintained in a horizontal state, and bent with a predetermined curvature radius using a bending die having a pin-shaped groove. In the secondary bending process, the bending product bent with the predetermined curvature radius is twisted using a bending tool having a flat roller shape.
As described above, the bent unit pipe assemblies are coupled to each other to manufacture the transfer duct having the curved central part.
As described above, according to the transfer duct of the related art, as two processes are employed in the procedure of bending the unit pipe assembly, the number of processes may be increased.
In addition, the dimension of the final product may be changed as the pipes are secondarily tilted while the shapes of the primarily bent pipes are maintained. If the dimension of the final product is changed, it is necessary to correct the bending product by applying additional physical force to the bending product (for example, a hydraulic jack).